Katrina Yuzefpolsky was 8 when a man dressed as Santa Claus shot her in the face and killed nine of her family members with guns and a homemade flamethrower at a Christmas Eve party in Southern California.

More than nine years later, Katrina is 17 and joining a growing number of teenagers who have survived gun violence and are demanding change to weapons laws. She and students across California and the U.S. are walking out of their schools for 17 minutes on Wednesday - each minute representing a victim of the Feb. 14 shooting at Marjory Stoneman Douglas High School in Parkland, Florida.

Katrina and her close friend created a video to help spread the word about the walkout at their school in Pasadena, telling peers that it's their "duty to stand together as a generation to demand change."

"I've lived through it, and I'm still living my life as best as I can," she said. "It's not stopping me, it's not instilling fear in me. I want that change. I don't want other families to go through what me and my family went through."

Katrina was the first one shot when her aunt's ex-husband, Bruce Pardo, burst into her grandparents' home on Christmas Eve in 2008. He immediately began shooting, then used the flamethrower to torch the house in Covina, 30 miles (48 kilometers) east of Los Angeles.

Pardo killed his ex-wife, who had recently divorced him, and eight of her relatives. He killed himself shortly afterward.

Katrina underwent surgery to remove bullet fragments and close the wound in her cheek that she got before escaping.

Her mother, Leticia Yuzefpolsky - who also escaped the massacre with her other daughter - has worked to make life as normal as possible for her girls and for her niece, whom she adopted after the girl's mother died in the attack.

She has tried to teach the girls not to give power to their family's killer, to continue celebrating Christmas, to associate Santa with good things, and to honor their loved ones by living life with purpose.

Katrina, a junior in high school, is doing just that. She loves playing softball and wants to keep it up in college while she studies business. She plans on going to an elite school, possibly Harvard or Amherst.

She tries not to sweat life's little irritations.

"I remind myself, 'I'm OK. These are minor details in my life. I will get through it,'" Katrina said. "I've survived being shot in the face, shot in the cheek, losing my family. A test is not going to break me."

Recently, she has been inspired by teenage survivors of the Florida shooting and their determination to effect change even though plenty of adults don't think they should have a say in the discussion over gun laws.

When her friend Bella Marez - also Pasadena's 100th Rose Queen - came up with an idea to make a video spreading the word about the walkouts, she immediately asked for Katrina's help.

"I really want our generation to wake up and say, 'We can make things happen and make long-lasting change,'" Bella said.

Katrina said the video and walkout have become part of her healing process.

"I know my family - my angels - are here watching me," she said. "They're seeing I'm finally going to make a difference and stand up for something that needs to be changed. I'm fighting for them."